1. Field of the Invention
This invention relates to valves, more particularly to process instrument isolation valves used in connection with toxic and corrosive materials.
2. Prior Art
In various industries, especially in the chemical industry, toxic and corrosive chemicals are used in a variety of ways. During processing of these chemicals, it is important to measure key properties of the chemicals including temperature and pressure. There are historical problems with the use of prior gauging methods. First, there is exposure of the toxic and corrosive chemicals to humans. Exposure can occur through numerous leak paths in the valves including the stem and any connection lines. Leaks also occur around the seals when the valves have monitors or sensors attached thereto. These leaks result in residual amounts of chemical being trapped within the valve body, sealed off from the tank or process lines, when the valve is operated. Second, there are multiple leak paths created by the use of multiple leak valves. When more than one property of a particular substance is to be measured, the leak paths are often multiplied by the number of different valves used. Thus, there exists a need for a single unit that can have interchangeable sensors where the changing of the sensors will not expose the operator to the toxic characteristics of the substance being measured.